| 摘要 |
PURPOSE:To improve cutting-off ability, by a method wherein a construction joint is excavated through injection of superhigh pessure water, a foreign matter layer, such as clay, is cut to form a cut groove, and an excavated hole, formed by the cut groove serving as a guide, is filled with a cut-off material. CONSTITUTION:A construction joint 11 between an existing concrete 9 and new concrete 10 is excavated with a jet of water and by means of a tip 3 to form an excavated hole 6. Excavation is effected down to a depth longer than a bore D of the excavated hole 6, and a cut groove 14 is formed along the construction joint part 11 by cutting a soft foreign matter layer 13, such as clay. A device A is pushed forward in the cut groove 14 as guide vanes 5 and 5' attached to a bit 2 are guided to form the excavated hole 6 with a given depth. Further, after the device A is pulled off, the excavated hole 6 is filled with a cut-off material. |
